Gymnasts on narrow beams, kids in helmets sliding around skate parks — these are dangerous pursuits, to be sure. But at least the wood and concrete don’t rise up and chase you, trying to hurl you onto a razor-sharp reef full of life and rake you over it like a meat grinder. Before the final rounds, Teahupo’o had already injured two surfers, and that was in cramped conditions, with a bigger swell planned to build. Australian Jack Robinson had five stitches in his foot, purely in training. The injury didn’t stop Robinson from knocking out American John John Florence in a heavyweight round 3 heat amid mounting surf that knocked them both out early. France’s Johanne Defay suffered a head injury in a heat on Saturday that required four stitches.

“It’s a cheese grater,” legendary big wave surfer Laird Hamilton said by phone from his home in Malibu, California. “If you fall, you’re going to kill yourself.”

Rest assured, if there are bigger waves in the quarterfinals, many surfers will… shall fall. “If it’s serious, it will take out most of the field,” Hamilton predicted.

Teahupo’o is the most philosophically interesting competition at the Paris Games, and not just because of the question of whether it’s right to impose a judge’s tower on surfers or to build it on a glittering coral reef. The place seems sacred. There’s something about the teeming energy in that wave dissolving into such a smooth glass cylinder. It restores the sense of power in that word, sacred, reminding you that it means something about true dominion.

“It’s the most perfect wave in the world and the most terrifying and evil wave in the world,” said Ramzi Boukhiam of Morocco. “It has two faces. You see it from the outside, you look at it from the boat and you think, ‘Wow, it’s beautiful.’ But when you’re inside, you fall, poof, it’s not as beautiful.”

In 2000, Hamilton stunned the world by riding Teahupo’o, now known as the “Millennium Wave.” A photo on the cover of Surfer magazine captured it, a murderous ridge of water hanging over Hamilton’s head with the caption, “oh my god…” The photo effectively opened Teahupo’o, previously ridden by only a handful of locals and elite pros, to the world. “It changed people’s perspective on what was rideable,” Hamilton said. The feeling of all that blue-green majestic energy was so profound that Hamilton cried afterward.

“It’s not so much the vastness of the wave,” Hamilton told me a few years ago about why he chases such seemingly unrideable masses. “It’s more about the insignificance of us. When you become insignificant, you really start to participate. Then it becomes a harmonious act.”

Peruvian surfer Sol Aguirre had a similar reaction when she jumped on a wave during training. At first she felt fear, but then it turned into this beautiful transparent tunnel and a cloud of white spray. “I started crying because it was a really beautiful ride, and I survived,” she said, according to the official Games website. “You come out and it’s like, ‘I’m alive. I’m alive.'”

A harmonious act. That’s what Teahupo’o really needs to bless riders. The wave can’t submit. Water is 800 times denser than air. Saltwater weighs 64 pounds per cubic foot. Combine that heft with Teahupo’o’s peculiar oceanography, and it creates a unique hydraulic problem: The wave is a cylinder of centrifugal inversion. It sucks water up from the base of the shallows, steep and powerful—and it will take you with it. Pick a line that’s too high, and the backspin from the water will grab your board and spin you up and over the falls. Even a small hit from that heavy edge can do a certain amount of damage: A year ago at training camp, New Zealander Saffi Vette went slightly forward on her board and snapped the edge right on the back of her leg. The impact was so hard that it tore her medial collateral ligament.

But if you survive the initial dive — the suction, the angle, the speed — it’s heaven. “That wave, because it comes up so fast, you have to get in early and prepare yourself to take the drop, the descent, and then pull in,” Hamilton said. “It’s all about the start. If you get a good start, you have a good chance and it can lead to a more dramatic ride. If someone does it well, it’s going to be an ease that deceives the difficulty.”

Ease, harmony — that’s what the competitors seem to feel when they’ve got the breakthrough right. The best, the ones who win a medal, will show a sense of cooperation with all that excitement. If Teahupo’o is going to be big, look at the Tahitians in the round of 16, Kauli Vaast in the men’s and Vahiné Fierro in the women’s. They’re the ones most familiar with it, have a regular acquaintance with the very edge of things there.

Why does Teahupo’o evoke such powerful emotions in surfers? Perhaps it’s partly a physical response, a release of tension. Surfing is an experience of full-body intensity. The transfer of all that metabolic high energy excites neuronal signals. We’re all creatures of light and electricity, and also tissue — inside us is a swarm of fireflies. The triggered chemical-emotional responses that come with stress produce a heightened clarity, an “alertness,” Hamilton said, “and we’re meant to experience that.”

Teahupo’o is a challenge, even on the easiest day. There is no better way. You don’t beat the ocean when you come home to those cliffs. You just work with it — until it lets you go.